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  • Journal article
    Sornig M, Sonnabend G, Stupar D, Kroetz P, Nakagawa H, Mueller-Wodarg Iet al., 2013,

    Venus' upper atmospheric dynamical structure from ground-based observations shortly before and after Venus' inferior conjunction 2009

    , ICARUS, Vol: 225, Pages: 828-839, ISSN: 0019-1035
  • Journal article
    Edberg NJT, Andrews DJ, Shebanits O, Agren K, Wahlund J-E, Opgenoorth HJ, Roussos E, Garnier P, Cravens TE, Badman SV, Modolo R, Bertucci C, Dougherty MKet al., 2013,

    Extreme densities in Titan's ionosphere during the T85 magnetosheath encounter

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 40, Pages: 2879-2883, ISSN: 0094-8276
  • Journal article
    Wen G, Cahalan RF, Haigh JD, Pilewskie P, Oreopoulos L, Harder JWet al., 2013,

    Reconciliation of modeled climate responses to spectral solar forcing

    , JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, Vol: 118, Pages: 6281-6289, ISSN: 2169-897X
  • Conference paper
    Fox C, Pickering JC, Green PD, Beeby R, Murray JE, Last Aet al., 2013,

    Studies of the far IR water vapour continuum from CAVIAR and RHUBC campaigns using TAFTS

    , OSA FTS

    We report results from the participation of the Imperial College TAFTS instrument in the CAVIAR and RHUBC field campaigns, validating a derived water vapor continuum parameterization in the far-IR spectral region.
  • Journal article
    Walsh AP, Arridge CS, Masters A, Lewis GR, Fazakerley AN, Jones GH, Owen CJ, Coates AJet al., 2013,

    An indication of the existence of a solar wind strahl at 10AU

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 40, Pages: 2495-2499, ISSN: 0094-8276
  • Journal article
    Ceppi P, Hwang Y-T, Liu X, Frierson DMW, Hartmann DLet al., 2013,

    The relationship between the ITCZ and the Southern Hemispheric eddy-driven jet

    , Journal of Geophysical Research: Atmospheres, Vol: 118, Pages: 5136-5146, ISSN: 2169-897X

    [1] We study the effect of a thermal forcing confined to the midlatitudes of one hemisphere on the eddy‐driven jet in the opposite hemisphere. We demonstrate the existence of an “interhemispheric teleconnection,” whereby warming (cooling) the Northern Hemisphere causes both the intertropical convergence zone (ITCZ) and the Southern Hemispheric midlatitude jet to shift northward (southward). The interhemispheric teleconnection is effected by a change in the asymmetry of the Hadley cells: as the ITCZ shifts away from the Equator, the cross‐equatorial Hadley cell intensifies, fluxing more momentum toward the subtropics and sustaining a stronger subtropical jet. Changes in subtropical jet strength, in turn, alter the propagation of extratropical waves into the tropics, affecting eddy momentum fluxes and the eddy‐driven westerlies. The relevance of this mechanism is demonstrated in the context of future climate change simulations, where shifts of the ITCZ are significantly related to shifts of the Southern Hemispheric eddy‐driven jet in austral winter. The possible relevance of the proposed mechanism to paleoclimates is discussed, particularly with regard to theories of ice age terminations.
  • Journal article
    Bradshaw SJ, Cargill PJ, 2013,

    THE INFLUENCE OF NUMERICAL RESOLUTION ON CORONAL DENSITY IN HYDRODYNAMIC MODELS OF IMPULSIVE HEATING

    , ASTROPHYSICAL JOURNAL, Vol: 770, ISSN: 0004-637X
  • Journal article
    Chen CHK, Bale SD, Salem CS, Maruca BAet al., 2013,

    Residual Energy Spectrum of Solar Wind Turbulence

    , The Astrophysical Journal, Vol: 770, Pages: 125-125, ISSN: 0004-637X
  • Journal article
    Bale SD, Pulupa M, Salem C, Chen CHK, Quataert Eet al., 2013,

    Electron Heat Conduction in the Solar Wind: Transition from Spitzer-Härm to the Collisionless Limit

    , The Astrophysical Journal Letters, Vol: 769, Pages: L22-L22, ISSN: 2041-8205
  • Journal article
    Chen CHK, Howes GG, Bonnell JW, Mozer FS, Klein KG, Bale SDet al., 2013,

    Kinetic Scale Density Fluctuations in the Solar Wind

    , AIP Conference Proceedings, Vol: 1539, Pages: 143-146

    We motivate the importance of studying kinetic scale turbulence forunderstanding the macroscopic properties of the heliosphere, such as theheating of the solar wind. We then discuss the technique by which kinetic scaledensity fluctuations can be measured using the spacecraft potential, includinga calculation of the timescale for the spacecraft potential to react to thedensity changes. Finally, we compare the shape of the density spectrum at ionscales to theoretical predictions based on a cascade model for kineticturbulence. We conclude that the shape of the spectrum, including the ion scaleflattening, can be captured by the sum of passive density fluctuations at largescales and kinetic Alfven wave turbulence at small scales.
  • Journal article
    Provan G, Cowley SWH, Sandhu J, Andrews DJ, Dougherty MKet al., 2013,

    Planetary period magnetic field oscillations in Saturn's magnetosphere: Postequinox abrupt nonmonotonic transitions to northern system dominance

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 3243-3264
  • Journal article
    Ray LC, Galand M, Delamere PA, Fleshman BLet al., 2013,

    Current-voltage relation for the Saturnian system

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 3214-3222, ISSN: 2169-9380
  • Journal article
    Matteini L, Hellinger P, Goldstein BE, Landi S, Velli M, Neugebauer Met al., 2013,

    Signatures of kinetic instabilities in the solar wind

    , Journal of Geophysical Research: Space Physics, Vol: 118, Pages: 2771-2782, ISSN: 2169-9380

    <jats:p>An analysis of ion non‐thermal properties in the fast solar wind based on Ulysses data is reported. The radial evolution of the main proton moments (density, temperature, and drift velocities) and their empirical correlations with other plasma parameters are investigated in detail and compared with theoretical expectations. The stability of the plasma is studied against different ion kinetic instabilities driven by ion temperature anisotropies and differential velocities, focusing on the identification of possible signatures of relevant instabilities in the observed core‐beam structure of proton distributions. The temperature anisotropy of the total proton distribution appears to be constrained by fire hose instabilities, in agreement with previous studies, while if considered separately, beam and core populations exhibit opposite anisotropies, with core protons characterized by perpendicular temperatures larger than the parallel ones, possibly (marginally) unstable for ion‐cyclotron instability. The evolution with distance of the drift velocity between the secondary population and the main core is found to be nonadiabatic, leading to the identification of a marginal stability path of a magnetosonic ion‐beam instability. As a conclusion, we find that a large fraction of the proton distributions observed by Ulysses display signatures of either a beam or a fire hose instability, suggesting that such kinetic processes play an important role in regulating the solar wind thermal energetics during the plasma expansion.</jats:p>
  • Journal article
    Balogh A, Erdos G, 2013,

    The Heliospheric Magnetic Field

    , SPACE SCIENCE REVIEWS, Vol: 176, Pages: 177-215, ISSN: 0038-6308
  • Journal article
    Eastwood JP, Phan TD, Drake JF, Shay MA, Borg AL, Lavraud B, Taylor MGGTet al., 2013,

    Energy Partition in Magnetic Reconnection in Earth's Magnetotail

    , PHYSICAL REVIEW LETTERS, Vol: 110, ISSN: 0031-9007
  • Journal article
    Chan NLA, Brindley HE, Ekins-Daukes NJ, 2013,

    Impact of individual atmospheric parameters on CPV system power, energy yield and cost of energy

    , Progress in Photovoltaics, Vol: 22, Pages: 1080-1095, ISSN: 1099-159X

    The performance of concentrator photovoltaic systems can be characterised by the power output under reference conditions and the output energy yield under realistic solar illumination. For a range of locations, the frequency distribution of individual atmospheric parameters and their quantitative impact on power output of a concentrator photovoltaic system have been evaluated, with aerosols shown to have a substantial impact on performance at many sites. Limited knowledge of atmospheric parameters results in a difference of up to 75% in simulated energy yield over an annual period and up to 75% deviation in the expected levelised cost of energy.
  • Journal article
    Naik V, Voulgarakis A, Fiore AM, Horowitz LW, Lamarque J-F, Lin M, Prather MJ, Young PJ, Bergmann D, Cameron-Smith PJ, Cionni I, Collins WJ, Dalsøren SB, Doherty R, Eyring V, Faluvegi G, Folberth GA, Josse B, Lee YH, MacKenzie IA, Nagashima T, van Noije TPC, Plummer DA, Righi M, Rumbold ST, Skeie R, Shindell DT, Stevenson DS, Strode S, Sudo K, Szopa S, Zeng Get al., 2013,

    Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    , Atmospheric Chemistry and Physics, Vol: 13, Pages: 5277-5298
  • Journal article
    Liu YD, Luhmann JG, Lugaz N, Moestl C, Davies JA, Bale SD, Lin RPet al., 2013,

    ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS

    , ASTROPHYSICAL JOURNAL, Vol: 769, ISSN: 0004-637X
  • Journal article
    Voulgarakis A, Shindell DT, Faluvegi G, 2013,

    Linkages between ozone-depleting substances, tropospheric oxidation and aerosols

    , Atmospheric Chemistry and Physics, Vol: 13, Pages: 4907-4916

    <jats:p>Abstract. Coupling between the stratosphere and the troposphere allows changes in stratospheric ozone abundances to affect tropospheric chemistry. Large-scale effects from such changes on chemically produced tropospheric aerosols have not been systematically examined in past studies. We use a composition-climate model to investigate potential past and future impacts of changes in stratospheric ozone depleting substances (ODS) on tropospheric oxidants and sulfate aerosols. In most experiments, we find significant responses in tropospheric photolysis and oxidants, with small but significant effects on methane radiative forcing. The response of sulfate aerosols is sizeable when examining the effect of increasing future nitrous oxide (N2O) emissions. We also find that without the regulation of chlorofluorocarbons (CFCs) through the Montreal Protocol, sulfate aerosols could have increased by 2050 by a comparable amount to the decreases predicted due to relatively stringent sulfur emissions controls. The individual historical radiative forcings of CFCs and N2O through their indirect effects on methane (−22.6 mW m−2 for CFCs and −6.7 mW m−2 for N2O) and sulfate aerosols (−3.0 mW m−2 for CFCs and +6.5 mW m−2 for N2O when considering the direct aerosol effect) discussed here are non-negligible when compared to known historical ODS forcing. Our results stress the importance of accounting for stratosphere-troposphere, gas-aerosol and composition-climate interactions when investigating the effects of changing emissions on atmospheric composition and climate. </jats:p>
  • Journal article
    Dhomse SS, Chipperfield MP, Feng W, Ball WT, Unruh YC, Haigh JD, Krivova NA, Solanki SK, Smith AKet al., 2013,

    Stratospheric O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; changes during 2001–2010: the small role of solar flux variations in a CTM

    <jats:p>Abstract. Solar spectral fluxes (or irradiance) measured by the SOlar Radiation and Climate Experiment (SORCE) show different variability at ultraviolet (UV) wavelengths compared to other irradiance measurements and models (e.g. NRL-SSI, SATIRE-S). Some modelling studies have suggested that stratospheric/lower mesospheric O3 changes during solar cycle 23 (1996–2008) can only be reproduced if SORCE solar fluxes are used. We have used a 3-D chemical transport model (CTM), forced by meteorology from the European Centre for Medium-Range Weather Forecasts (ECMWF), to simulate middle atmospheric O3 using three different solar flux datasets (SORCE, NRL-SSI and SATIRE-S). Simulated O3 changes are compared with Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite data. Modelled O3 anomalies from all solar flux datasets show good agreement with the observations, despite the different flux variations. The off-line CTM reproduces these changes through dynamical information contained in the analyses. A notable feature during this period is a robust positive solar signal in the tropical middle stratosphere due to changes in stratospheric dynamics. Ozone changes in the lower mesosphere cannot be used to discriminate between solar flux datasets due to large uncertainties and the short time span of the observations. Overall this study suggests that, in a CTM, the UV variations detected by SORCE are not necessary to reproduce observed stratospheric O3 changes during 2001–2010. </jats:p>
  • Journal article
    Ceppi P, Hartmann DL, 2013,

    On the speed of the eddy-driven jet and the width of the hadley cell in the Southern Hemisphere

    , Journal of Climate, Vol: 26, Pages: 3450-3465, ISSN: 0894-8755

    A strong correlation between the speed of the eddy-driven jet and the width of the Hadley cell is found to exist in the Southern Hemisphere, both in reanalysis data and in twenty-first-century integrations from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report multimodel archive. Analysis of the space–time spectra of eddy momentum flux reveals that variations in eddy-driven jet speed are related to changes in the mean phase speed of midlatitude eddies. An increase in eddy phase speeds induces a poleward shift of the critical latitudes and a poleward expansion of the region of subtropical wave breaking. The associated changes in eddy momentum flux convergence are balanced by anomalous meridional winds consistent with a wider Hadley cell. At the same time, faster eddies are also associated with a strengthened poleward eddy momentum flux, sustaining a stronger westerly jet in midlatitudes. The proposed mechanism is consistent with the seasonal dependence of the interannual variability of the Hadley cell width and appears to explain at least part of the projected twenty-first-century trends.
  • Journal article
    Branduardi-Raymont G, Ford PG, Hansen KC, Lamy L, Masters A, Cecconi B, Coates AJ, Dougherty MK, Gladstone GR, Zarka Pet al., 2013,

    Search for Saturn's X-ray aurorae at the arrival of a solar wind shock

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 2145-2156, ISSN: 2169-9380
  • Journal article
    Andres N, Gomez DO, Bertucci C, Mazelle C, Dougherty MKet al., 2013,

    Saturn's ULF wave foreshock boundary: Cassini observations

    , PLANETARY AND SPACE SCIENCE, Vol: 79-80, Pages: 64-75, ISSN: 0032-0633
  • Journal article
    Zhong J, Pu ZY, Dunlop MW, Bogdanova YV, Wang XG, Xiao CJ, Guo RL, Hasegawa H, Raeder J, Zhou XZ, Angelopoulos V, Zong QG, Fu SY, Xie L, Taylor MGGT, Shen C, Berchem J, Zhang QH, Volwerk M, Eastwood JPet al., 2013,

    Three-dimensional magnetic flux rope structure formed by multiple sequential X-line reconnection at the magnetopause

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 1904-1911, ISSN: 2169-9380
  • Journal article
    Bowman KW, Shindell DT, Worden HM, Lamarque JF, Young PJ, Stevenson DS, Qu Z, de la Torre M, Bergmann D, Cameron-Smith PJ, Collins WJ, Doherty R, Dalsøren SB, Faluvegi G, Folberth G, Horowitz LW, Josse BM, Lee YH, MacKenzie IA, Myhre G, Nagashima T, Naik V, Plummer DA, Rumbold ST, Skeie RB, Strode SA, Sudo K, Szopa S, Voulgarakis A, Zeng G, Kulawik SS, Aghedo AM, Worden JRet al., 2013,

    Evaluation of ACCMIP outgoing longwave radiation from tropospheric ozone using TES satellite observations

    , Atmospheric Chemistry and Physics, Vol: 13, Pages: 4057-4072
  • Journal article
    Hellinger P, Trávníček PM, Štverák Š, Matteini L, Velli Met al., 2013,

    Proton thermal energetics in the solar wind: Helios reloaded

    , Journal of Geophysical Research: Space Physics, Vol: 118, Pages: 1351-1365, ISSN: 2169-9380

    <jats:p>The proton thermal energetics in the slow solar wind between 0.3 and 1 AU is reinvestigated using the Helios 1 and 2 data, complementing a similar analysis for the fast solar wind [Hellinger et al., 2011]. The results for slow and fast solar winds are compared and discussed in the context of previous results. Protons need to be heated in the perpendicular direction with respect to the ambient magnetic field from 0.3 to 1 AU. In the parallel direction, protons need to be cooled at 0.3 AU, with a cooling rate comparable to the corresponding perpendicular heating rate; between 0.3 and 1 AU, the required cooling rate decreases until a transition to heating occurs: by 1 AU the protons require parallel heating, with a heating rate comparable to that required to sustain the perpendicular temperature. The heating/cooling rates (per unit volume) in the fast and slow solar winds are proportional to the ratio between the proton kinetic energy and the expansion time. On average, the protons need to be heated and the necessary heating rates are comparable to the energy cascade rate of the magnetohydrodynamic turbulence estimated from the stationary Kolmogorov‐Yaglom law at 1 AU; however, in the expanding solar wind, the stationarity assumption for this law is questionable. The turbulent energy cascade may explain the average proton energetics (although the stationarity assumption needs to be justified) but the parallel cooling is likely related to microinstabilities connected with the structure of the proton velocity distribution function. This is supported by linear analysis based on observed data and by results of numerical simulations.</jats:p>
  • Journal article
    Zhong W, Haigh JD, 2013,

    The greenhouse effect and carbon dioxide

    , WEATHER, Vol: 68, Pages: 100-105, ISSN: 0043-1656
  • Journal article
    Grasset O, Dougherty MK, Coustenis A, Bunce EJ, Erd C, Titov D, Blanc M, Coates A, Drossart P, Fletcher LN, Hussmann H, Jaumann R, Krupp N, Lebreton J-P, Prieto-Ballesteros O, Tortora P, Tosi F, Van Hoolst Tet al., 2013,

    JUpiter ICy moons Explorer (JUICE): An ESA mission to orbit Ganymede and to characterise the Jupiter system

    , PLANETARY AND SPACE SCIENCE, Vol: 78, Pages: 1-21, ISSN: 0032-0633
  • Journal article
    Simon S, van Treeck SC, Wennmacher A, Saur J, Neubauer FM, Bertucci CL, Dougherty MKet al., 2013,

    Structure of Titan's induced magnetosphere under varying background magnetic field conditions: Survey of Cassini magnetometer data from flybys TA-T85

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 1679-1699, ISSN: 2169-9380
  • Journal article
    Sergis N, Jackman CM, Masters A, Krimigis SM, Thomsen MF, Hamilton DC, Mitchell DG, Dougherty MK, Coates AJet al., 2013,

    Particle and magnetic field properties of the Saturnian magnetosheath: Presence and upstream escape of hot magnetospheric plasma

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 1620-1634, ISSN: 2169-9380

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